Rear Main Seal Woes

[James B.]

I have a '67 L-79 Coupe with 52,000 miles. Had a metallic 'click- click' sound at idle & after ruling everything else out concluded it had to be cam gear/chain. As recommended here bought a Cloyes double roller chain and so far it looks good. The cam gear was badly worn, 50+% nylon gone, aluminum teeth chewed up and chain stretched. The sound was the chain slapping against the timing cover (strange thing is it ran well; timing had to be off 5-10 degrees).

Of course, had to take down the pan and I knew the rear seal was leaking so why not do that too. Now i've got the rear main cap off but cannot get the top half of the seal out. I've tried tapping the edge with a screw driver but no movement. The edge is flush with the block & I can't get needle nose pliers on it to try to pull it out. After 43 years the varnish has it welded to the block.
If I can't figure out something I'll have to pull all the main caps trying to let the crank down far enough to get some clearance, but I am not eager to do that.

Can anyone help with ideas on a procedure or tool that could help? I will appreciate any help. Thanks, JimB

[Clem Z.]

Re: Rear Main Seal Woes

I have a '67 L-79 Coupe with 52,000 miles. Had a metallic 'click- click' sound at idle & after ruling everything else out concluded it had to be cam gear/chain. As recommended here bought a Cloyes double roller chain and so far it looks good. The cam gear was badly worn, 50+% nylon gone, aluminum teeth chewed up and chain stretched. The sound was the chain slapping against the timing cover (strange thing is it ran well; timing had to be off 5-10 degrees).

Of course, had to take down the pan and I knew the rear seal was leaking so why not do that too. Now i've got the rear main cap off but cannot get the top half of the seal out. I've tried tapping the edge with a screw driver but no movement. The edge is flush with the block & I can't get needle nose pliers on it to try to pull it out. After 43 years the varnish has it welded to the block.
If I can't figure out something I'll have to pull all the main caps trying to let the crank down far enough to get some clearance, but I am not eager to do that.

Can anyone help with ideas on a procedure or tool that could help? I will appreciate any help. Thanks, JimB

try spaying something like KROIL and let it soak around the edge to free up the seal

[James B.]

Re: Rear Main Seal Woes

Yes, Clem, good idea & thanks. I also thought about getting a small nozzle for an air hose; I can pry the seal away from the block a little and will try compressed air in the gap after soaking it.

[Timothy B.]

Re: Rear Main Seal Woes

James,

When you replace the seal do NOT use FelPro 2900, get the GM seal and seal the main cap with permatex ultra black as shown in the directions. Seal part # is in archives.. Make sure you clean the crankshaft journal to be sure all is smooth.

Also, use the little shoe horn that comes with the seal to install the new seal so you don't nick the back sealing area when it's slid into the block and cap.

[Jim D.]

Re: Rear Main Seal Woes

James,

When you replace the seal do NOT use FelPro 2900, get the GM seal and seal the main cap with permatex ultra black as shown in the directions. Seal part # is in archives.. Make sure you clean the crankshaft journal to be sure all is smooth.

Also, use the little shoe horn that comes with the seal to install the new seal so you don't nick the back sealing area when it's slid into the block and cap.

Just curious why recommend not using the FP 2900. I've used it and the FP 11829 (seems like they include either one in their gasket kits). Never had one leak.

Jim

[Joe C.]

Re: Rear Main Seal Woes

Can't see a problem with the 2900, although I have used the 2912....flouroelastomer.

[James B.]

Re: Rear Main Seal Woes

Interesting and helpful comments. I bought two seals and remember that one is the FP 2900. The other one is offset and maybe FP11829-1 (don't have it here at home). However, the crank is fine, not grooved at all.

Reading here and the archives sounds like the most recommended is the FP 2912 flouroelastomer seal. Jim Durham recommended the GM seal but the archives seem to say that (GM 10121044) and the FP 2912 are the same and the GM seal is made by Fel-Pro (Jim, are you talking about another GM seal??).

I will get a FP 2912 and permatex ultra black tomorrow.

Any further creative ideas on getting the old one out will be appreciated. Thanks to all for the input. JimB

[Edward J.]

Re: Rear Main Seal Woes

I have a '67 L-79 Coupe with 52,000 miles. Had a metallic 'click- click' sound at idle & after ruling everything else out concluded it had to be cam gear/chain. As recommended here bought a Cloyes double roller chain and so far it looks good. The cam gear was badly worn, 50+% nylon gone, aluminum teeth chewed up and chain stretched. The sound was the chain slapping against the timing cover (strange thing is it ran well; timing had to be off 5-10 degrees).

Of course, had to take down the pan and I knew the rear seal was leaking so why not do that too. Now i've got the rear main cap off but cannot get the top half of the seal out. I've tried tapping the edge with a screw driver but no movement. The edge is flush with the block & I can't get needle nose pliers on it to try to pull it out. After 43 years the varnish has it welded to the block.
If I can't figure out something I'll have to pull all the main caps trying to let ,the crank down far enough to get some clearance, but I am not eager to do that.

Can anyone help with ideas on a procedure or tool that could help? I will appreciate any help. Thanks, JimB

Jim, I have replaced many rear main seals over the years in my automotive business, they do tend to almost weld them selfs to the block, there is a tool that I brought many years ago , it had a plastic handle with a aluminun rod molded to the handle, The rod was about the side of a 3/16 drill bit. since the rear seals have a metal rod that is molded in the middle of the seal, you have something to use for tapping, it is hard to see the rod but is there.

So find a suitiable small dia aluminun rod and or maybe one of the locol automotive stores may have a rear seal remover and installer kit, (cheap money). I think the company- KD tool makes them.

remember the crankshaft can be damaged so take your time when removing, The seal may have been replaced at sometime, If so a non- harding sealer or sealant could have been used. Since you removed the main caps this may help make the job easier, You can pry the rear of the crankshaft down slightly- but will require removel of the upper thrust bearing. GOOD LUCK - ED

[Timothy B.]

Re: Rear Main Seal Woes

James,

I can only relate my experence with the Fel Pro 2900 seal and after being very careful installing and sealing the cap it leaked.

Using the GM seal there were no more problems, and I am sure this seal was developed for a good reason. Check archives as we have been down this road before and there is good info for you..


Google Fel Pro 2900 leak and see what others have experenced.. I don't know if the seal is to soft or to hard except to say it leaked on my car..After all your hard work for a few $$ more it's the best seal..

I also used a VERY small coat of ultra black on both sides of the oil pan gasket and both sides of the rubber seals front and back, no more leak or seepage. Be careful with the ultra black because it will clog the oil pump pick up screen if it gets inside the engine..

[Clem Z.]

Re: Rear Main Seal Woes

also make sure you use non hardening permatex on the area marked xxxx shown below or you could still have a leak. DO NOT use RTV use non hardening permatex part #80019

[James B.]

Re: Rear Main Seal Woes

Again, thanks to all for the info and advice. I have also found a rear main seal tool. It is like a little corkscrew- the diameter no more than 1/8" so you screw this up between the seal and the block and pull the seal out- will try it tomorrow morning & post the results of my efforts. JimB

[Edward J.]

Re: Rear Main Seal Woes

Again, thanks to all for the info and advice. I have also found a rear main seal tool. It is like a little corkscrew- the diameter no more than 1/8" so you screw this up between the seal and the block and pull the seal out- will try it tomorrow morning & post the results of my efforts. JimB

Jim, the rear seal tool you have is for the Rope type rear seal. don't use this type, find yourself a old screw driver cut the tip of and use the blunt end to drive the seal out. just remember the the screw driver is harden steel don't let it get driven to deep just enough to start the seal outward, Then use the needle nose pliers to pull and remove.

[Gerry P.]

Re: Rear Main Seal Woes

Jim - When I changed mine, I used a small wooden dowel (maybe 1/4") and used it as a punch to break the seal loose and push it up and around enough that I could get a good grip on the other end. Being wooden, I wasn't concerned about damaging the crank.